Gasoline composition containing a multipurpose additive



United States Patent 3,223,497 GASOLINE COMPOSITION CONTAINING A MULTIPURPOSE ADDITIVE Robert E. Malec, Chicago, 111., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Filed Aug. 31, 1961, Ser. No. 135,160 3 Claims. (CI. 44-70) This invention relates to a gasoline composition and more particularly to a gasoline composition containing an additive and exhibiting anti-rust, de-icing, detergent, and anti-gum forming properties.

A serious rusting problem exists when gasolines are in contact with ferrous metals. Illustrations of such situations are storage tanks, pipe lines, and automotive gasoline tanks. An additional problem exists when gasoline is kept in storage tanks. A water layer generally exists and causes additional rusting in the metallic storage tank. These two types of rusting not only cause the ferrous metals to deteriorate, but also cause contaminants to form in the gasoline. These contaminants, products of the rusting, generally require removal or will cause the clogging and malfunctioning of the important parts of a gasoline engine. Attempts have been made to overcome the two types of rusting such as dehydrating the gasoline and draining of the water phase from the storage tank. These methods have not been entirely satisfactory and provide only temporary relief from the problems.

Engine stalling due to carburetor icing is another problem associated with gasoline. Ice forms on the throttle plate in the carburetor in cool humid weather and restricts or closes the air passage in the carburetor. This problem is particularly acute during idling when the throttle is closed. The driver of the automobile can restart the engine after stalling, but this is not a satisfactory solution to the problem.

Gasolines also contain gum formers which cause deposits to form on internal parts of the fuel system such as are in the carburetor. These deposits build up on many of the internal parts of the carburetor and seriously restrict or plug many of its small openings. Attempts have been made to reduce the build up of these deposits such as the use of additives to limit the gum content of the gasoline; however, the results have not been entirely satisfactory.

Additional gum deposits also normally form in the intake manifold and intake valves of a gasoline engine. These deposits coat the surfaces of the valves and cause malfunctioning of these important automotive parts. Additives have been added to gasolines in an attempt to overcome this problem, but have not eliminated it completely.

' One object of this invention is to improve the anti-rust properties of gasoline. Another object is to reduce the formation of carburetor ice. Still another object is to reduce the deposits formed from gum contained in gasoline. An additional object is to reduce the formation of gum deposits in the intake manifold and intake valves of a gasoline engine. An important object is to simultaneously improve the anti-rust and de-icer properties of gasoline and reduce the gum forming and gum deposit tendencies of gasoline. Other objects of this invention will be apparent from the detailed description.

It has been discovered that a gasoline which contains a lithium salt of a monoaliphatic'ester of a particular polycarboxylic acid exhibits improved anti-rust and de-icer properties and reduced gum forming and gum deposit tendencies. The backbone of the acid is a member of the group consisting of aliphatic compounds having at least 2 carbon atoms and cycloaliphatic compounds having at least 3 carbon atoms. The acid has at least 2 carboxy groups and contains only carbon, hydrogen, and

oxygen atoms, while the carboxy groups contain the only carbonyl groups in the acid. The aliphatic radical of the ester has from about 6 to about 30 carbon atoms and contains only carbon and hydrogen atoms. The lithium is in the form of a salt with at least 1 carboxy group of the acid.

The gasoline, i.e., a liquid fuel, used in this invention may be any commonly made by the petroleum industry. Gasoline is generally characterized as a hydrocarbon boiling between an initial ASTM boiling point of about F. and an ASTM end point of about 450 F., and more usually an ASTM end point of about 400 F. Common blending stocks are virgin andcracked naphthas and reformate; these may be used individually or blended. Any hydrocarbon boiling within the gasoline range may be used. In addition, the gasolines may contain additives such as lead alkyl anti-knock agents, lead scavenging agents, dyes and spark plug-fouling inhibitors.

The gasoline of the invention contains a lithium salt of a monoaliphatic ester of a polycarboxylic acid wherein the backbone of the acid is a member of the group consisting of aliphatic compounds having at least 2 carbon atoms and cycloaliphatic compounds having at least 3 carbon atoms. The aliphatic compounds may contain 60 or more carbon atoms although it is preferred that the aliphatic compounds contain from 2 to about 10 carbon atoms and the cycloaliphatic compounds contain from 3 to about 10 carbon atoms. The acid has at least 2 carboxy groups and contains only carbon, hydrogen, and oxygen atoms. It is preferred that the backbone structure be aliphatic and especially alkyl or alkenyl. The backbone may contain various substituent groups such as hydroxy and alkoxy groups, the only restriction being that the acid contains only carbon, hydrogen, and oxygen atoms and that the carboxy groups in the acid contain the only carbonyl groups. Illustrative radicals for the backbone are: ethyl, propyl, propenyl, cyclopropyl, cyclohexyl, octyl, decenyl, pentacosyl, and hexacontyl radicals.

The acid contains at least 2 carboxy groups and may contain as many as 5 or more carboxy groups although it preferably contains 2 to 3 carboxy groups. Illustrations of the acid including the backbone structure are: 1,2- ethanedicarboxylic acid (succinic), 2,3-propenedicarboxylic acid (itaconic), Z-hydroxy-1,2,3-propanetricarboxylic acid (citric), 1,2,3-propenetricarboxylic acid (acouitic), 1,2,3 propanetricarboxylic acid (tricarballylic), l,2,3-cyclopropanetricarboxylic acid, 1,2,3,4,5- heptenepentacarboxylic acid and 1-propyl-2,3,4,5,6-cyclohexanepentacarboxylic acid.

The aliphatic radical of the ester contains from about 6 to about 30 carbon atoms and preferably from about 10 to about 18 carbon atoms. This radical contains only carbon and hydrogen atoms. It is preferred that the radical be either alkyl or alkenyl. Illustrations of these .ester radicals are: monohexyl, monooctyi, monodecyl,

monotridecyl, monohexadecyl, monooctadecyl, monooctadecenyl, and monotriacontyl.

The lithium is present as a salt with at least 1 carboxy group of the acid. It is preferred that the lithium salt be reacted with only 1 carboxy group thus producing a monolithium salt. Illustrations of the salts of this invention are: dilithium salt of monodecylcitrate, trilithium salt of monodecyl heptenepentacarboxylate, monolithium salt of monodecylaconitate, monolithium salt of monotridecylaconitate, monolithium salt of monooctylaconitate, and monolithium salt of monodecylitaconate.

The lithium salt of the invention is present in the gasoline in amounts sufficient to improve the anti-rust and deicer properties. Commonly the amounts of the salt in the gasoline range from about 1 lb. to about 500 lbs. per

1000 barrels (42 gal.) of the gasoline and more specificalaconitate.

. 3 1y from about lbs. to about 1.50 lbs. per 1000 barrels. from about 5 lbs. to about 150 lbs. per 1000 barrels. Typically, it has been found with the monolithium salt of monodecylaconitate that an amount of from about 5 lbs. to about 150 lbs. per 1000 barrels of gasoline gives especially good results.

EXAMPLES Illustrative embodiments of the salts of this invention were prepared and then blended into gasoline samples for testing. The monoesters of the acid were first prepared and then the monolithium salt was formed. One example was the formation of the monolithium salt of monodecylaconitate. It was prepared by heating 1 mole of citric acid and 1.1 moles of decyl alcohol in an inert solvent, namely, xylene. The reaction was carried out at about 284% F., the water of reaction being distilled overhead and the xylene returned to the system. After approximately 8 hours the solution was cooled to approximately 75 F. The water of reaction was recovered and found to be 2 moles of water which indicated that the monoesters of aconitic acid were formed.

330 grams of a 50% (by weight) xylene solution of monodecylaconitate was then reacted with 20 grams of lithium carbonate dissolved in 20 grams of water. The mixture was stirred for approximately 16 hours at 75 F after which refluxing was carried out at 284 F. for approximately 2 hours. The carbon dioxide of reaction bubbled off during the 16 hour period. The water of reaction and the water used in dissolving the lithium carbonate were removed overhead during the refluxing oper ation. The remaining solution was cooled to approximately 75 F., and filtered to remove solids which had formed during the removal of water. The solution was analyzed and found to contain 0.6% lithium. This was determined to be approximately 60% of the amount of lithium necessary to react with the monodecylaconitate. Thus, the solution was a mixture of the monolithium salt of monodecylaconitate and the unreacted monodecyl- In addition to the monolithium salt of monodecylaconitate, the following salts were prepared in this manner: The monolithium salt of monotridecylaconitate, the monolithium salt of monooctylaconitate, the monosodium salt of monodecylaconitate and the monolithium salt of monodecylitaconate. (A trifluoride-etherate catalyst was used in the above procedure to prepare the monodecylitaconate.)

' Gasoline compositions were prepared by blending the xylene solution of each of the above prepared lithium salts into commercial grades of premium gasoline. The compositions were then tested for their tendencies to form rust, ice, and gum deposits.

The base gasoline used for the Rust Test, Gum Deposit Test, and Gum Formation Test contained 2.7 cc. of TEL fluid per gallon of gasoline, and 2 lbs. of commercial anti-oxidant and 1 lb. of metal deactivator per 1000 barrels 'of gasoline. The gasoline had the following ASTM Distillation: Initial, 104 F.; 133 F.; 50%, 206 F.; 90%, 309 F.; and maximum, 385 F. The base gasoline used in the Icing Test was a commercial winter grade gasoline containing 2.5 cc. of TEL per gallon of gasoline, and 5 lbs. of commercial antioxidant and 2 lbs. of metal deactivator per 1000 barrels of gasoline. The gasoline had the following ASTM Distillation: Initial, 84 F.; 10%, 101 F.; 50%, 185 F.; 90%, 300 F.; and maximum 376 F.

Rust test The Rusting Test used was the Static Rust Test which consists of placing 100 ml. of sample into a 4 oz. bottle, inserting a /2 x 5 x 0.01 polished black iron strip into the bottle, allowing the strip and sample to stand for 30 minutes, pipeting 10 ml. of water into the bottle, placing a stopper into the bottle opening, rolling the bottle on its side for one minute, standing the bottle on end, tapping the bottle several times to knock down water globules adhering to the strip and sides of the bottle, and setting the bottle aside for a duration of 24 hours after which the degree of rust on the strip is determined and graded according to the following ratings.

Rating Oil Phase Water Phase NMT 2 Spots 05% Rust. NMT 6 Spots 545% Rust. NMT 10 Spots 1550% Rust. MT 10 Spots 50100% Rust.

The test results from 5 gasoline compositions are listed in Table I below including a control sample.

TABLE I.STATIO RUST TEST RESULTS The above results from Table I demonstrate that the anti-rust properties of a gasoline are improved with the addition of the lithium salts of this invention. The remarkable effectiveness of the lithium salts is shown by the change in rusting value from 4 to 1.

Icing test The effectiveness of the lithium salt of this present invention in preventing or reducing engine stalling due to carburetor icing is demonstrated by the results obtained in the operation of a V8 1958 Plymouth automobile engine. In this test the engine is operated with a fuel inlet temperature of 38-40 F., an intake air temperature of 40:1 F., and a relatively humidity of -95%. The engine is started cold and accelerated to 1500 r.p.m. in seven seconds and maintained at that speed for 30 seconds. The engine is then decelerated to idle r.p.m. in seven seconds and idled for about 15 seconds. This cycle is repeated until three successive idle periods are free of stalls and engine roughness. Engine stalling and/ or buckings characteristics are observed and recorded. If the engine stalls it is immediately restarted and run through the described cycle. The number of stalls and number of rough idle periods prior to the three smooth idle periods are recorded and the mean icing severity is calculated. The main icing severity is the sum of the number of stalls plus one-half the number of rough idle periods.

Gasoline compositions of this invention and a control sample were tested in accordance with the above tested procedure to determine the effectiveness of the additive to reduce carburetor icing. The results from the test are listed in Table H below.

TABLE II.-DE-ICING TEST RESULTS These results in Table II show that the icing severity was reduced from 14 to 5 or over 50% by the addition of lbs. of lithium salt per 1000 barrels of gasoline.

This demonstrates the effectiveness of the lithium salts of this invention as de-icers.

Gum deposit test Gasoline compositions of this invention and control samples were tested for existent gum by the ASTM D381 Test. In this test, 50 ml. of sample are placed in a beaker and evaporated at 311:90 F. until a residue is produced. The residue is washed with normal heptane and dried at 31119" F. for 5 minutes. The existent gum content of the gasoline is reported as milligrams of existent gum per 100 ml. of sample. Thus, the test measures the detergency eiTect of an additive in dispersing the existing gum residue in normal heptane.

The results of ASTM D381 tests are listed below in Table 111 including those from control samples. Compositions containing sodium decylaconitate were also tested for comparison purposes.

TABLE III.-AS'IM D-381 GUM TEST RESULTS 00110., Existent Test Additive lbs/1,000 No. um No. bbl. Tests (mg/100 4 1. 4 Lithium decylaconitate. 100 i 0. 8 0. Lithium deeylaconitate 100 4 5 Lithium decylaconitate 50 4 1. 5 Lithium tridecylaconitate... 50 4 0. 4 Sodium decy1aconitate 50 2 5. 1 Lithium decylaconitate 75 2 1. 3 Lithium octylaconitate. 75 2 2. 6 Lithium tridecylaconitate 75 2 1.1 Sodium decylaconitate 75 g 'ililifiiiiii21365566555661 I 4 11 2 Lithium tridecylaconitate--. 50 2 1. 2 Lithium decylitaconate. 67 2 0. 4

The results from Table III above demonstrate the effectiveness of the lithium salts of this invention. As can be seen from the Tests Nos. 12-15, the presence of the lithium decylaconitate (100 lbs. per 1000 barrels) reduced the gum residue completely to zero. The results from Test Nos. 16-23 demonstrated that the sodium salt was worse than having no additive in the gasoline.

Gum formation test The effectiveness of the gasoline compositions of this invention in eliminating the formation of gum in the intake manifold and intake valves of engines was demonstrated by running tests using a Lauson engine. The procedure used is described in a paper entitled, Evaluating Gasolines for Induction System Gums, by C. C. Moore, J. L. Keller, W. C. Kent and F. S. Liggett, presented before the SAE National Fuels and Lubricants Meeting in Tulsa, Oklahoma, held November 4-5, 1954 (available as Preprint No. 406 from the SAE Special Publications Department). The test method described correlates very well with a full-scale engine tests in measuring undesirable Test Fuel Manifold, Valve, No. mg. mg.

28 Gasoline 72 29 Gasoline containing lbs. of 21 32 lithium decylaconitate per 1,000 bbls.

The results from Table IV above show that the addition of the lithium salt to the gasoline causes over a 50% reduction in the gum deposits formed on the manifold and the intake valves of the Lauson engine.

In addition to the above test, the gasoline compositions of this invention were tested for their effect on octane number. The test results showed that the additive caused a slight increase in the octane number (0.1-0.5 unit).

The results of the tests described above demonstrate quite efiectively that the additive is highly beneficial to gasoline in that it simultaneously reduces four important problems associated with gasoline.

Thus having described the invention, what is claimed is:

1. A liquid fuel comprising a major portion of hydrocarbon boiling within the gasoline range and from about 1 lb. to about lbs. per 1000 barrels of said hydrocarbon, of a lithium salt of a monoaliphatic ester of a polycarboxylic acid wherein the backbone of said acid is a member of the group consisting of alkyl and alkenyl compounds having from 2 to about 10 carbon atoms, said acid having 3 carboxy groups and only carbon, hydrogen, and oxygen atoms, said carboxy groups containing the only carbonyl groups in said acid, said aliphatic radical of said ester being selected from the group consisting of alkyl and alkenyl radicals; having from about 10 to about 18 carbon atoms and only carbon and hydrogen atoms and said lithium forming a monolithium salt.

2. The fuel of claim 1 wherein said salt is monolithium monodecylaconitate.

3. The fuel of claim 1 wherein said salt is monolithium DANIEL E. WYMAN, Primary Examiner. 

1. A LIQUID FUEL COMPRISING A MAJOR PORTION OF HYDROCARBON BOILING WITHIN THE GASOLINE RANGE AND FROM ABOUT 1 LB. TO ABOUT 150LBS. PER 1000 BARRELS OF SAID HYDROCARBON, OF A LITHIUM SALT OF A MONOALIPHATIC ESTER OF A POLYCARBOXYLIC ACID WHEREIN THE BACKBONE OF SAID ACID IS A MEMBER OF THE GROUP CONSISTING OF ALKYL AND ALKENYL COMPOUNDS HAVING FROM 2 TO ABOUT 10 CARBON ATOMS, SAID ACID HAVING 3 CARBOXY GROUPS AND ONLY CARBON, HYDROGEN, AND OXYGEN ATOMS, SAID CARBOXY GROUPS CONTAINING THE ONLY CARBONYL GROUPS IN SAID ACID, SAID ALIPHATIC RADICAL OF SAID ESTER BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ALKENYL RADICALS; HAVING FROM ABOUT 10 TO ABOUT 18 CARBON ATOMS AND ONLY CARBON AND HYDROGEN ATOMS AND SAID LITHIUM FORMING A MONOLITHIUM SALT. 